+1, would also enjoy a book recommendation. I can recommend a fun app - Euclidea :) My favorite book on the topic, unfortunately only in Slovak, is: "Matemati

+1, would also enjoy a book recommendation. I can recommend a fun app - Euclidea :) My favorite book on the topic, unfortunately only in Slovak, is: "Matematici, ja a ty" (mathematicians, you and me). I don't think there is a translation. I also had a university professor who had a similar style - not dry proofs, but "Here is how Archimedes thought about proofs" - which is related to the comment above: if A is not smaller than B and B is not smaller than A, they need to be equal.